ESA: Astrophysicist Anthony Marston one of the minds behind ESA Science

Excellence and perseverance - astrophysicist Anthony Marston is one of the brilliant minds behind ESA Science

Astronomers release unprecedented data set on celestial objects that brighten and dim

This is an image of a dwarf nova, which is a star system where material flows from a red giant star to a dense, compact star called a white dwarf. 

The flowing material triggers explosions that cause the system to flare up as seen from Earth.

The graph shows the change in brightness of this system over a period of seven years. 

The images at the top show the nova at its brightest and dimmest, as indicated in the plot. 

Such systems are important for understanding stellar evolution, and the CRTS team has discovered nearly a thousand of them‑‑more than any other survey. 

Credit: The CRTS Survey Team, Caltech

ESA ESO VLT: Newborn Massive Stars Dwarf Full-Grown Stellar Giants

Artist’s impression illustrating the formation process of massive stars. 

At the end of the formation process, the surrounding accretion disk disappears, revealing the surface of the young star. 

At this phase the young massive star is much larger than when it has reached a stable equilibrium.

CREDIT: Lucas Ellerbroek/Lex Kaper University of Amsterdam

Massive stars generally start out life much bigger than they will be in maturity, a new study seems to confirm.

Astronomers from the University of Amsterdam got a rare look at a massive star in the process of forming and found that the star will contract until it has reached a stable equilibrium.

The researchers studied the young star B275, which lies in the Omega Nebula, also called the Swan Nebula or Messier 17. This hotbed of gas, dust and young stars lies approximately 5,500 light-years from Earth, in the direction of the Sagittarius constellation.

Astronomers typically struggle to obtain clear observations of a massive star as it is forming, since newborn stars are deeply embedded and obscured in their parent clouds of gas and dust.

Peering through the haze
To lift the veil on the process of star formation, the researchers sifted through ultraviolet and infrared data collected from a powerful spectrograph instrument, called the X-shooter, on the European Space Agency's Very Large Telescope at the Paranal Observatory in Chile.

"The large-wavelength coverage of X-shooter provides the opportunity to determine many stellar properties at once, like the surface temperature, size, and the presence of a disk," study lead author Bram Ochsendorf said in a statement.

Ochsendorf analyzed the data as part of his master's research project at the University of Amsterdam.

The results indicate that B275 is about three times larger than stars that are about seven times more massive than our sun and have reached the so-called main sequence phase of their lives.

The main sequence phase represents a specific stage of stellar evolution in which a star burns hydrogen into helium. (Our own sun is currently in its main sequence.)

The team's findings appear to confirm a theory of star formation predicting that a newly formed massive star will contract until it reaches a more stable state.

NASA Hubble: First Supernova Companion Star Found

An international team of astronomers has, for the first time, observed a stellar "survivor" to emerge from a double star system involving an exploded supernova.

Supernovae are some of the most significant sources of chemical elements in the universe, and they are at the heart of our understanding of the evolution of galaxies.

In this artist's view the red super-giant supernova progenitor star (left) is exploding after having transferred about 10 solar masses of hydrogen gas to the blue companion star (right).

Image Credit: NASA

The Heart Of Cygnus Fermi: A Cosmic-ray Cocoon

Cygnus X hosts many young stellar groupings, including the OB2 and OB9 associations and the cluster NGC 6910. 

The combined outflows and ultraviolet radiation from the region's numerous massive stars have heated and pushed gas away from the clusters, producing cavities of hot, lower-density gas.

In this 8-micron infrared image, ridges of denser gas mark the boundaries of the cavities. Bright spots within these ridges show where stars are forming today. Credit: NASA/IPAC/MSX.

The constellation Cygnus, now visible in the western sky as twilight deepens after sunset, hosts one of our galaxy's richest-known stellar construction zones.

Astronomers viewing the region at visible wavelengths see only hints of this spectacular activity thanks to a veil of nearby dust clouds forming the Great Rift, a dark lane that splits the Milky Way, a faint band of light marking our galaxy's central plane.

Located in the vicinity of the second-magnitude star Gamma Cygni, the star-forming region was named Cygnus X when it was discovered as a diffuse radio source by surveys in the 1950s.

Now, a study using data from NASA's Fermi Gamma-ray Space Telescope finds that the tumult of star birth and death in Cygnus X has managed to corral fast-moving particles called cosmic rays.

Cosmic rays are subatomic particles - mainly protons - that move through space at nearly the speed of light. In their journey across the galaxy, the particles are deflected by magnetic fields, which scramble their paths and make it impossible to backtrack the particles to their sources.

Yet when cosmic rays collide with interstellar gas, they produce gamma rays - the most energetic and penetrating form of light - that travel to us straight from the source.

By tracing gamma-ray signals throughout the galaxy, Fermi's Large Area Telescope (LAT) is helping astronomers understand the sources of cosmic rays and how they're accelerated to such high speeds. In fact, this is one of the mission's key goals.

The galaxy's best candidate sites for cosmic-ray acceleration are the rapidly expanding shells of ionized gas and magnetic field associated with supernova explosions. For stars, mass is destiny, and the most massive ones - known as types O and B - live fast and die young.

They're also relatively rare because such extreme stars, with masses more than 40 times that of our sun and surface temperatures eight times hotter, exert tremendous influence on their surroundings.

With intense ultraviolet radiation and powerful outflows known as stellar winds, the most massive stars rapidly disperse their natal gas clouds, naturally limiting the number of massive stars in any given region.

Which brings us back to Cygnus X. Located about 4,500 light-years away, this star factory is believed to contain enough raw material to make two million stars like our sun.

Within it are many young star clusters and several sprawling groups of related O- and B-type stars, called OB associations.

One, called Cygnus OB2, contains 65 O stars - the most massive, luminous and hottest type - and nearly 500 B stars.

Astronomers estimate that the association's total stellar mass is 30,000 times that of our sun, making Cygnus OB2 the largest object of its type within 6,500 light-years. And with ages of less than 5 million years, few of its most massive stars have lived long enough to exhaust their fuel and explode as supernovae.

Intense light and outflows from the monster stars in Cygnus OB2 and from several other nearby associations and star clusters have excavated vast amounts of gas from their vicinities.

The stars reside within cavities filled with hot, thin gas surrounded by ridges of cool, dense gas where stars are now forming.

It's within the hollowed-out zones that Fermi's LAT detects intense gamma-ray emission, according to a paper describing the findings that was published in the journal Science.

NASA Fermi Reveals a Cosmic-ray Cocoon in Cygnus - YouTube

Tour the Cygnus X star factory. This video opens with wide optical and infrared images of the constellation Cygnus, then zooms into the Cygnus X region using radio, infrared and gamma-ray images. Fermi LAT shows that gamma rays fill cavities in the star-forming clouds. The emission occurs when fast-moving cosmic rays strike hot gas and starlight.

ESA & NASA's Hubble Confirms That Galaxies Recycle

Distant quasars shine through the gas-rich "fog" of hot plasma encircling galaxies. 

At ultraviolet wavelengths, Hubble's Cosmic Origins Spectrograph (COS) is sensitive to absorption from many ionized heavy elements, such as nitrogen, oxygen, and neon.

COS's high sensitivity allows many galaxies that happen to lie in front of the much more distant quasars. The ionized heavy elements serve as proxies for estimating how much mass is in a galaxy's halo.

(Credit: NASA; ESA; A. Feild, STScI).

New observations by NASA's Hubble Space Telescope are expanding astronomers' understanding of the ways in which galaxies continuously recycle immense volumes of hydrogen gas and heavy elements. This process allows galaxies to build successive generations of stars stretching over billions of years.

This ongoing recycling keeps some galaxies from emptying their "fuel tanks" and stretches their star-forming epoch to over 10 billion years.

This conclusion is based on a series of Hubble Space Telescope observations that flexed the special capabilities of its Cosmic Origins Spectrograph (COS) to detect gas in the halo of our Milky Way and more than 40 other galaxies.

Data from large ground-based telescopes in Hawaii, Arizona and Chile also contributed to the studies by measuring the properties of the galaxies.

Astronomers believe that the color and shape of a galaxy is largely controlled by gas flowing through an extended halo around it. The three studies investigated different aspects of the gas-recycling phenomenon.

A Starry Sky in Castille, Spain

Spanish Photographer Martin Zalba's photo shows a windmill against a starry sky in Castille. 

View more of his photographs on Flickr.

Picture: Martin Zalba / Barcroft Media

Milky Way's Stellar 'Jewel box' - NGC3603

Thousands of young stars nestle within the giant nebula NGC 3603.

This stellar "jewel box" is one of the most massive young star clusters in the Milky Way Galaxy.

NGC 3603 is a prominent star-forming region in the Carina spiral arm of the Milky Way, about 20,000 light-years away.

This image shows a young star cluster surrounded by a vast region of dust and gas. The image reveals stages in the life cycle of stars. The nebula was first discovered by Sir John Herschel in 1834. The image spans roughly 17 light-years.

Picture: NASA

ESA Hubble: Bright new Star

The pearly wisps surrounding the central star IRAS 10082-5647 in this Hubble image certainly draw the eye towards the heavens.

The divine-looking cloud is a reflection nebula, made up of gas and dust glowing softly by the reflected light of nearby stars, in this case a young Herbig Ae/Be star.

The star, like others of this type, is still a relative youngster, only a few million years old. It has not yet reached the so-called main sequence phase, where it will spend around 80% of its life creating energy by burning hydrogen in its core.

Until then the star heats itself by gravitational collapse, as the material in the star falls in on itself, becoming ever denser and creating immense pressure which in turn gives off copious amounts of heat.

Stars only spend around 1% of their lives in this pre-main sequence phase. Eventually, gravitational collapse will heat the star’s core enough for hydrogen fusion to begin, propelling the star into the main sequence phase, and adulthood.

The Advanced Camera for Surveys aboard the Hubble Space Telescope captured the whorls and arcs of this nebula, lit up with the light from IRAS 10082-5647. Visible (555 nm) and near-infrared (814 nm) filters were used, coloured blue and red respectively. The field of view is around 1.3 by 1.3 arcminutes.

Credit:ESA/Hubble, NASA

Brown Drawf: Rogue Failed Star Is One of Smallest Ever Seen

Extreme brightness changes observed on a nearby tiny brown dwarf star may indicate a storm grander than any yet seen on an alien world, scientists say.

CREDIT: Jon Lomberg

Astronomers have discovered more than two dozen previously unknown failed stars, including one that ranks among the puniest of its kind, new research finds.

The newfound objects are brown dwarfs, strange bodies that are larger than planets but too small to trigger the internal nuclear fusion reactions required to become full-fledged stars.

Astronomers discovered the objects in two young star clusters using Japan's Subaru Telescope in Hawaii and the Very Large Telescope in Chile.

One of the brown dwarfs is just six times the mass of Jupiter, making it "one of the puniest free-floating objects known," researchers said in a statement.

NASA & ESA Hubble: Offers a Dazzling Necklace Nebula

A giant cosmic necklace glows brightly in this NASA/ESA Hubble Space Telescope image.

The object, aptly named the Necklace Nebula, is a recently discovered planetary nebula, the glowing remains of an ordinary, Sun-like star.

The nebula consists of a bright ring, measuring about two light-years across, dotted with dense, bright knots of gas that resemble diamonds in a necklace.

The knots glow brightly due to absorption of ultraviolet light from the central stars.

A pair of tightly orbiting stars produced the nebula, also called PN G054.2-03.4. About 10 000 years ago one of the aging stars ballooned to the point where it engulfed its companion star.

The smaller star continued orbiting inside its larger companion, increasing the giant’s rotation rate, so that the bloated star span so fast that a large part of its gaseous envelope expanded into space. Most of the gas escaped along the star’s equator, producing a ring. The bright knots are dense gas clumps in the ring.

The pair is so close, only a few million kilometres apart, that they appear as one bright dot in the centre of this image. The stars are furiously whirling around each other, completing an orbit in a little more than a day.

For comparison, Mercury, the innermost planet of our Solar System, orbits the Sun in 88 days.

The Necklace Nebula is located 15 000 light-years away in the constellation of Sagitta (The Arrow). In this composite image, taken on 2 July, Hubble’s Wide Field Camera 3 captured the glow of hydrogen (blue), oxygen (green), and nitrogen (red).

Credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)

NASA Hubble: Dazzling 'Necklace' Nebula

The Necklace Nebula is located 15,000 light-years away in the constellation Sagitta (the Arrow). 

In this composite image, taken on July 2, 2011, Hubble's Wide Field Camera 3 captured the glow of hydrogen (blue), oxygen (green), and nitrogen (red). 

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

A giant cosmic necklace glows brightly in this NASA Hubble Space Telescope image.

The object, aptly named the Necklace Nebula, is a recently discovered planetary nebula, the glowing remains of an ordinary, Sun-like star.

The nebula consists of a bright ring, measuring 12 trillion miles wide, dotted with dense, bright knots of gas that resemble diamonds in a necklace.

A pair of stars orbiting close together produced the nebula, also called PN G054.2-03.4. About 10,000 years ago one of the aging stars ballooned to the point where it engulfed its companion star. The smaller star continued orbiting inside its larger companion, increasing the giant’s rotation rate.

The bloated companion star spun so fast that a large part of its gaseous envelope expanded into space. Due to centrifugal force, most of the gas escaped along the star’s equator, producing a ring. The embedded bright knots are dense gas clumps in the ring.

The pair is so close, only a few million miles apart, they appear as one bright dot in the center. The stars are furiously whirling around each other, completing an orbit in a little more than a day.

The Necklace Nebula is located 15,000 light-years away in the constellation Sagitta. In this composite image, taken on July 2, Hubble’s Wide Field Camera 3 captured the glow of hydrogen (blue), oxygen (green), and nitrogen (red).

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Neutron Stars Are Doomed if Vacuum Energy goes out of control

Artist's illustration of an "isolated neutron star"--a neutron star that does not have an associated supernova remnant, binary companion or radio pulsations. Credit: Casey Reed/Penn State University.

A mind-bogglingly huge buildup of "vacuum energy," which would occur in just milliseconds, could lead the stellar remnants known as neutron stars to instantly collapse or explode, scientists now suggest.

What is often thought of as the empty vacuum of space is actually filled with ghostly energy and virtual particles wavering in and out of existence, a bizarre prediction of quantum theory that numerous experiments have proven true.

This "vacuum energy," as scientists call it, is usually thought of as extremely weak at best. But theoretical physicists in Brazil suggest that the immensely powerful gravitational fields of neutron stars could "awaken the vacuum," causing its energy to build up exponentially very quickly.

Brilliant Star In A Colourful Neighbourhood of Carina Nebula

This image of part of the Carina Nebula was created from images taken through red, green and blue filters with the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile.

It is centred on the unusual hot massive young star WR 22, a member of the rare class of Wolf-Rayet stars.

The field of view is 0.55 x 0.55 degrees, covering a 72 x 72 light-year region at the distance of the nebula.

Credit: ESO

Very massive stars live fast and die young. Some of these stellar beacons have such intense radiation passing through their thick atmospheres late in their lives that they shed material into space many millions of times more quickly than relatively sedate stars such as the Sun.

These rare, very hot and massive objects are known as Wolf-Rayet stars, after the two French astronomers who first identified them in the mid-nineteenth century, and one of the most massive ones yet measured is known as WR 22.

It appears at the centre of this picture, which was created from images taken through red, green and blue filters with the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile. WR 22 is a member of a double star system and has been measured to have a mass at least 70 times that of the Sun.

WR 22 lies in the southern constellation of Carina, the keel of Jason's ship Argo in Greek mythology. Although the star lies over 5000 light-years from the Earth it is so bright that it can just be faintly seen with the unaided eye under good conditions.

WR 22 is one of many exceptionally brilliant stars associated with the beautiful Carina Nebula (also known as NGC 3372) and the outer part of this huge region of star formation in the southern Milky Way forms the colourful backdrop to this image.

The subtle colours of the rich background tapestry are a result of the interactions between the intense ultraviolet radiation coming from hot massive stars, including WR 22, and the vast gas clouds, mostly hydrogen, from which they formed